Method for producing a part and device for carrying out this method

ABSTRACT

The present invention relates to a method for producing a part ( 108, 200, 300 ), comprising the following steps:
         a) applying a first flat layer consisting of a support material ( 102, 202, 302 ), to a construction platform ( 101, 201, 301 ),   b) introducing at least one recess ( 103, 203, 303 ) into the support material ( 102, 202, 302 ),   c) filling the recess ( 103, 203, 303 ) with a construction material ( 104, 204, 304 ),   d) applying a further layer of support material ( 102, 202, 302 ),   e) repeating steps b) through d) until completion of the part ( 108, 200, 300 ), and   f) removing the support material ( 102, 202, 302 ).       

     This method is to provide a manufacturing method and a device that combine the advantages of the layerwise construction (rapid prototyping) with the advantages of machining (e.g. high-speed cutting) and particularly permit the production of sharp-edged contours. 
     Furthermore, the present invention relates to a device for carrying out the method.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a method for producing a part and to adevice for carrying out said method. Particularly, the invention relatesto a generative manufacturing method for producing metallic or compositeparts.

In the past years many different generative methods for the direct orindirect production of mostly non-metallic parts were developed andpartly commercialized.

Since in the direct manufacture of metallic parts the necessary progresshas not been achieved up to now, metallic parts, particularly those withcomplicated geometries, are even nowadays mostly produced in indirectmethods, such as precision casting or sand casting, which have alreadybeen known for a long time.

The most wide-spread method for the direct manufacture of metallic partsis milling or cutting. With the considerable speed increases provided byhigh-speed cutting (HSC), the attempt has already been made to combinesaid technology with other methods.

Due to the process chains that are often long in indirect methods (e.g.precision casting), there is a demand for methods for the directproduction of metal parts. Furthermore, there is a great demand forflexible methods for the fast and direct production of metal parts inseries material. Nowadays, however, this is often ruled out by problemsarising in generative manufacturing methods, e.g. objectionable stepeffect, porous parts, small constructional space, poor surface quality,inadequate accuracy, demand for a mechanical finishing operation,stresses and distortion, restricted use of series material, only limitedproduction of undercuts, no local use of different constructionmaterials, inadequate properties of the materials, only limitedproduction of functional parts.

Known direct methods for producing metallic articles are for example:

-   -   Laser generation with wire: The material is here applied by        metal wires that are locally molten by means of a laser. This        method belongs to the build-up welding methods. The part is here        built up in lines and layers, e.g. controlled metal build up        (CMB).    -   Laser generation with powder: The material is here applied by        metal powder that is locally molten by means of a laser. The        part is built up in lines and layers; e.g. laser engineering net        shaping (LENS) or direct light fabrication (DLF).    -   Laser sintering in the power bed: Particles that are closely        located side by side are molten with the help of a laser beam.        Depending on the type of the powder or powder mixture there are        various variants. The sintering of single-component metal powder        is e.g. designated as direct metal laser sintering (DMLS) or        laser power remelting (SLPR). A polymer-clad metal powder is        used in the sintering of multi-component metal polymer powders.        The polymer claddings are here molten to connect the particles        in order to obtain a green part. In a successive process the        polymer amount must be expelled and the part must be        infiltrated. In the sintering of multi-component metal-metal        powder a mixture is used that consists of low-melting and        high-melting metal powders.    -   Layer-laminate method: Foils are here used as construction        material that are glued or soldered; e.g. DE 197 29 770 C1,        layer milling process (LMP), laminated object manufacturing        (LOM).    -   3D printing method: Metal powder is here printed with binder.        The part produced in this way must be debindered and infiltrated        with metal, e.g. three-dimensional printing (3DP).    -   Micro-casting deposition: Layers are applied with the help of        masks by thermal spraying, e.g. micro-casting deposition (MD).

Furthermore, combinations of applying and removing methods are known(cf. e.g. EP 554 033 B1). A further approach consists in segmenting andconventionally milling the parts, e.g. stratified object manufacturing(SOM) or DE 197 27 934 A1.

In (almost) all of the known methods, particularly when rotating toolsare used, the tool diameter has an effect (depending on its geometry) onthe geometry of the parts insofar as it is not the desired geometry, buta geometry with radii that is created. Even in methods in which thecontour is produced by means of a laser, there is no sharp edge becausethe laser beam is most of the time rotationally symmetrical and the zoneof action (e.g. of the melt area) is larger than the beam. Even inmethods such as the 3D printing the drop radius has to be put up with.

It is therefore the object of the present invention to provide a methodfor producing a part as well as a device that combine the advantages ofthe layerwise construction (rapid prototyping) with the advantages ofmachining (e.g. high-speed cutting) and permit, in particular, theproduction of sharp-edged contours.

As far as the method is concerned, this object is achieved by thefeatures of claim 1 and, as far as the device is concerned, it isachieved by the features of claim 12.

In comparison with the conventional manufacturing methods, the method ofthe invention according to claim 1 has a number of advantages. A kind of“layer form” is created in the processing of the support material. Thelayer form may be designed such that a finishing operation is perhapsnot needed. This machining of the support material instead of theconstruction material permits an easier and faster chip removal. Toolwear is low. Smaller tool diameters can also be used. In case theconstruction material is difficult to machine or cannot be machined atall, for instance because of great hardness, the problem can beeliminated by way of shaping through the support material.

Thanks to the combination of support material processing andconstruction material processing, sharp-edged contours can be realized.Since larger milling diameters can be used, time can be saved as well.

In parts with a conventionally high chip removal rate, less volume mustbe machined.

The surface can preferably be leveled by milling with coarse tools. Thispermits a fast machining. A leveling operation is essential in order toproduce a defined start surface for the next layer or to ensure thesurface quality and dimensional stability if said surface or partsthereof represent the surface of the article to be produced. The surfacemay also be leveled by other mechanical methods or chemical or physicalremoval.

Thanks to a small layer thickness a dry machining with gaseous media canpreferably be carried out for chip removal, cleaning and cooling. Theuse of liquid cooling or lubricating substances should be dispensedwith, so that these need also not be removed again prior to theapplication of the next layer.

With the method of the invention it is possible to remove all kinds ofmetals, alloys, but also other materials (such as ceramics) in anydesired sequence by means of a single device system and thus to producethe most different characteristics within a construction body. Thanks tothe use of different materials with different characteristics, it ispossible to integrate, for instance, bearing bushes of any desiredgeometry in a form-fit or adhesive way into the housing, and to produceporous portions e.g. for lubricant absorption, for instance by anintelligent process control, in a similar way as in sintered materials.

It may here be necessary that the surface onto which the next layer isapplied is activated. This can e.g. be done by abrasive blasting, laserroughening or chemical processes within a single device system. Themethod of the invention and the associated device make it possible torealize constant or variable layer thicknesses, in dependence upon thegeometry, the application method, the thermal characteristics, thepredetermined tolerances, etc., within one part.

Moreover, it is possible to produce recesses, such as pockets or bores,also over several layers, to be able to introduce installation orinsertion parts that are fixedly or loosely connected to the basicstructure.

With a defined heating and cooling, characteristics, such as porosity,material structure, hardness, can also be adjusted locally in aselective way.

The method of the invention and the associated device make it possiblefor special applications to produce hollow bodies or double-walledbodies, or e.g. to integrate structures such as cooling channels.Movable functional parts can also be produced, e.g. through a thin gapduring production or by way of material combinations that do notinterconnect, or by the formation of gaps due to defined shrinkage of amaterial.

Both ceramics (e.g. polymer ceramics), plaster or (low-melting) metalsand alloys can preferably be used as the support material. The supportmaterial can be applied by spraying or printing. Of course, othermaterials and known methods are also possible.

Preferred are support materials that are (water-)soluble and liquid(easily flowing). After their solidification they should be(water-)soluble again. Of advantage would also be materials that arefast-setting or solidifying. They should also be resistant to heat.Desirable would also be some kind of shrinkage that is as small aspossible and thermal expansion that is as low as possible. Solubilitymay e.g. be accomplished by way of alkaline solutions or other media.

The support material can be applied by means of different applicationmethods. Said application methods can be subdivided into differentgroups:

1. Planar application and subsequent production of the requiredrecesses, for instance a.) planar spraying and milling of a recess(recesses), or b.) application of a layer, e.g. ceramic particles,application of a binder at the places where no recess is needed, andsubsequent sucking off of unbound particles. (The contour can e.g. befinished in addition, if necessary).

2. Application of portions and subsequent finishing of the recessesneeded, e.g. spraying portions and milling recess(es).

3. Application of support material in a defined way without finishing ofthe needed contour/recess, e.g. application of a layer in a defined waywith metering systems, e.g. drop-on-demand push button.

4. Application of support material in a defined way and finishing of theneeded contour/recess, e.g. application of the layer in a defined waywith metering systems, such as drop-on-demand push button, and finishingby way of milling.

The recesses can be produced to have a final size (if no allowance isdesired) or they may be made correspondingly larger by way of anallowance for a finishing operation. However, said final size or themeasure with the allowance is independent of the geometry of the wallsor of finishing work.

In all cases the contour can be applied and/or finished such that eithervertical walls/steps are created or the contour (walls) is approximatedto the desired contour (walls) for minimizing the step effect, oranother geometry that is formed due to the application/finishing methodor can be produced easily. A reworking of the layers in their height canbe carried out in all variants at any time, if necessary.

The form and number of the recesses depend on the geometry of the partand can of course also include e.g. islands. If several parts aremanufactured at the same time (e.g. side by side), said recesses areobtained by analogy for each part.

The part that is designed as a substrate may also be part of the articleto be produced. In this case said part is not separated from thelayerwise part (at least for the time being). The intermediate layers ofsupport material can optionally be omitted in this special case.

The construction material (powder) is filled with a device into therecesses produced. To this end different application methods can beused. Some of the possible application methods shall now be described ina few words.

An example of an application method is the method of thermal sprayingthat has been known for a long time. Thermal spraying includes e.g.flame spraying and arc spraying, plasma spraying, high-speed flamespraying, detonation spraying and laser spraying. During thermalspraying the spraying material is molten completely or partly in a gunby a flame, plasma or arc and flung out of the gun at a high speed. Thesuccessively impinging particles form a lamella-like layer withinclusion of pores. The adhesion of the spraying particles is due tomechanical interlocking, adhesion and chemical and metallurgicalinteractions. Mechanical interlocking normally makes the greatestcontribution to adhesion. The problem of adhesion can be solved by amelt-metallurgical connection by a subsequent melting of the new layerin itself and with the layer of construction material positionedthereunder, e.g. with the help of a laser. A problem arising in thethermal spraying at high temperatures is the oxide formation of theconstruction material. Since the use of inert gas (e.g. argon) as anatomizer gas is mostly not economic in the amounts needed, a certainoxide content in the construction material must be accepted.

A development of the high-speed flame spraying is cold gas spraying.This method is e.g. described in EP 484 533 B1. In cold gas spraying,powder is used as an additional material. In cold gas spraying, however,the powder particles are not molten in the gas jet because thetemperature of the gas jet is most of the time below the temperature ofthe melting point of the powder particles.

A further application method is the group of build-up welding. Since noatomizer gas is needed here, it is possible to work under an inert gasatmosphere to avoid the formation of oxide. The energy for melting orwelding can e.g. be introduced by a laser or an arc. The constructionmaterial may e.g. be supplied in the form of powder, rods or from aroll.

Especially in combination with the features of claim 8, a method isobtained that has a number of advantages over known sintering methods.

In the conventional selective laser sintering in a powder bed, theproblem arises that neighboring particles are molten or partly molten inan unintended way. This is detrimental to the surface quality anddimensional stability. In the novel method there are no neighboringparticles. Thus, no neighboring powder can be caked either. Furthermore,it is possible to finish the surface on the construction material. (Thisyields a better surface quality and a higher dimensional stability).

In the conventional selective laser sintering in the powder bed, thereis further the problem that the layer thickness and the geometry of thepart define the step effect. In the novel method, either the supportmaterial can be approximated to the ideal geometry of the part or thepart can be approximated to the ideal geometry of the part by finishingthe surface. (This leads to a minimization of the step effect, a bettersurface quality and a higher dimensional stability).

In the conventional selective laser sintering in the powder bed, thereis the problem that the energy input must be controlled exactly to limitcaking of the surrounding particles as much as possible. In the novelmethod there are no neighboring particles. Hence, neighboring powdercannot cake either. The process can be expedited by increasing theenergy input. (This creates the possibility of increasing the speed andprovides an unproblematic control of the energy input).

In the conventional selective laser sintering in the powder bed, thereis also the problem that enough energy must be introduced on the onehand so as to melt the powder, and an excessive amount of energy mustnot be introduced on the other hand so as to avoid caking of thesurrounding particles as much as possible. It is therefore oftenaccepted that the powder is only partly molten at least to some extent.In the novel method there are no neighboring particles. Hence,neighboring powder cannot cake even in the case of an increased energyinput. Due to the unproblematic melting of the particles, it is possibleto produce a part with the density and characteristics as are indicatedin the material specifications. (This makes it possible to produce partshaving a density of 100% (no porosity) and parts with improvedcharacteristics of the material.

In the conventional selective laser sintering in the powder bed, thereis the problem that sharp edges cannot be produced in part. In the novelmethod, the sharp edges can already be provided in the supportmaterial—at least in part—or realized by a possible finishing operationon the construction material. (In the novel method it is possible torealize sharp edges).

In the conventional selective laser sintering in the powder bed, thereis the problem that no insertion parts can be realized. (In the novelmethod it is possible to integrate insertion parts).

In the conventional selective laser sintering in the powder bed, thereis the problem that a combination of different materials cannot berealized without the powder being contaminated with the other. (In thenovel method there is the possibility of combining different materialsalso within one layer).

To avoid defects or voids (e.g. by oxidation) in the part, it ispossible to work e.g. under a protective gas atmosphere/inert gas or invacuum.

The powder can generally be molten by the supply of energy, e.g. byelectromagnetic radiation. A laser is preferably used.

Specific scanning strategies are useful or necessary to achieve desiredcharacteristics for part and material (e.g. overlapping of the tracks toobtain a higher density (low porosity portion)).

The manufacturing method of the invention is a combination of applyingand removing production methods and comprises the following processsteps:

1. Construct or digitize the part on the computer with a 3D-CAD system

2. Numerically decompose 3D-drawing/data into layers (e.g. 0.25 mm)

3. Read processed data into the machine.

Steps 1 and 3 are here identical with the preparations that are nowadaysstandard for a CNC manufacture or production with generative systems.Step 2 is needed for a layerwise construction. In principle, this isalso known, but in much coarser steps, from the segmented manufacturewith conventional millers (e.g. DE 197 27 934 A1). When the preparatorysteps are taken into account, the method shown in its entirety actuallystarts with the 4^(th) step:

4. Apply support material (e.g. inorganic or organic substances,low-melting alloy) to construction platform (e.g. by spraying). Ifnecessary, activate the surface of the construction platform before.

5. After the support material has solidified (e.g. by setting, cooling),apply the next layer of support material.

6. Repeat step 5 so often that a sufficient height is obtained to removethe part from the platform at a later time or to insulate it thermally.

7. Level surface (e.g. by milling).

8. Apply layer of support material, if possible, in one operation (e.g.by spraying or printing).

9. After the support material has solidified (e.g. by setting, cooling),produce recess in the support material for the construction material(e.g. by milling). If undercuts in the support material are neededbecause of the geometry, produce vertical walls at said places. Adaptall of the other walls, if possible, to the final geometry (minimizationof the step effect) or provide, if necessary, an allowance for the finalgeometry. If sharp edges are required on the construction material, makerecess larger according to processing allowance.

10. If necessary, level and/or activate surface.

11. Apply construction material (powder) (e.g. by thermal spraying, coldgas spraying, build-up welding method).

12. If due to the application method there is e.g. no melt-metallurgicalconnection in itself and/or relative to the base, or the layer is porousor has cracks, melt or weld new layer in itself and optionally with thelayer positioned thereunder through a source of energy (e.g.electromagnetic radiation, preferably laser beam).

13. If necessary, level surface of the layer (e.g. by milling).

14. If sharp edges are to be produced on the construction material or ifan allowance was taken into account before, produce these now (e.g. bymilling) or finish the same.

15. If necessary, remove the undercuts that would be created in thesupport material in dependence upon the geometry, now or simultaneouslywith step 14 on the construction material (e.g. by milling). Due to thevertical walls more material has been applied than needed. This materialis now removed).

16. Repeat steps 7 to 15 until the part has reached its overall height.In case voids were produced in the support material by processingoperations (e.g. undercuts, sharp edges, allowance), these voids arealso filled with the application of the support material for the nextlayer.

17. Separate part with support material from the construction platform.

18. Remove block from the machine.

19. Remove support material to expose part (e.g. by dissolution,melting, mechanical removal).

If two or more different construction materials are to be used perlayer, the second and each successive material must be introduced intothe layer like the first construction material. To this end part of thealready applied construction material or support material must possiblybe removed again to create some space for the further constructionmaterial.

If the part is to have a higher surface quality (than would be obtainedwith the separation relative to the support material), or also for otherreasons, the recess in the support material is made larger in accordancewith a processing allowance. After the construction material hashardened, the final dimension and the final surface of the part are thenproduced in the area of the layer in a further step. To this end thesupport material must also be removed again in part.

The support material can also be applied in a defined way to minimize oravoid finishing work.

To form contours, millers or grinding tools are preferably used. Whetherform millers are used, or inclinations are e.g. achieved by incliningthe tool, these measures come up to the same. The predominant processingof a support material that can be machined more easily, instead of ahigh-quality construction material, effects faster machinability, lowertool wear and offers the possibility of using smaller tool diameters, ifnecessary. Sharp-edged contours can be realized by combining supportmaterial and construction material. If e.g. in this case larger millerdiameters are used, this will save time in every corresponding process.

Since the chip removal for the construction material can be reduced to aminimum, high-quality construction material can be saved.

Removal processes can be carried out not only mechanically, but alsowith chemical or physical methods.

The facing of every layer is preferably performed with coarse tools fora faster machining operation. It is here only of importance that adefined layer thickness and a defined start surface are obtained for thenext step.

For an automatic process monitoring, known sensors may be used (e.g.optical or thermal ones). They must just be of such a type that theyensure process reliability and the observation of tolerances.

The base of the system consists preferably of a conventional triaxialCNC milling machine with automatic tool changer. The machine is extendedwith devices for applying and optionally for processing the supportmaterial and the construction material. For instance, depending on thekind of construction material application a laser is integrated formelting the layers. All of the important additional means (except forsupply means) are located within the fully encapsulated casing of themilling machine.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference toembodiments.

FIG. 1 is a sectional view where the construction material is just beingapplied in the form of powder;

FIG. 2 is a sectional view where the construction material was applied;

FIG. 3 is a sectional view where the construction material is just beingmolten with a laser;

FIG. 4 is a sectional view where the construction material was molten;

FIG. 5 is a sectional view where the uppermost layer was leveled;

FIG. 6 is a sectional view of an article to be produced;

FIG. 7 is a top view on the substrate and a preceding layer;

FIG. 8 is a sectional view of FIG. 7;

FIG. 9 is a top view on a further step of the method, wherein thesupport material was applied to the substrate;

FIG. 10 is a sectional view of FIG. 9;

FIG. 11 is a top view on a further step of the method, wherein a recesswas produced in the support material;

FIG. 12 is a sectional view of FIG. 11;

FIG. 13 is a top view on a further step of the method, wherein therecess in the support material was filled with construction material;

FIG. 14 is a sectional view of FIG. 13;

FIG. 15 is a top view on a further step of the method, wherein a sharpedge was produced on the part;

FIG. 16 is a sectional view of FIG. 15;

FIG. 17 is a top view on a further step of the method, wherein a newlayer of support material was applied;

FIG. 18 is a sectional view of FIG. 17, where the new layer of supportmaterial can be recognized as a layer-overlapping ply;

FIG. 19 is a sectional view of an article to be produced;

FIG. 20 is a top view on the substrate or a preceding layer;

FIG. 21 is a sectional view of FIG. 20;

FIG. 22 is a top view on a further step of the method, wherein supportmaterial was applied to the substrate;

FIG. 23 is a sectional view of FIG. 22;

FIG. 24 is a top view on a further step of the method, wherein a recesswas produced in the support material;

FIG. 25 is a sectional view of FIG. 24;

FIG. 26 is a top view on a further step of the method, wherein therecess in the support material was filled with construction material;

FIG. 27 is a sectional view of FIG. 26;

FIG. 28 is a top view on a further step of the method, wherein theallowance on the part was removed;

FIG. 29 is a sectional view of FIG. 28;

FIG. 30 is a top view on a further step of the method, wherein a newlayer of support material was applied; and

FIG. 31 is a sectional view of FIG. 30, where the new layer of supportmaterial can be recognized as a layer-overlapping ply.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 to 5 depict the production of a part 108 according to a firstpreferred embodiment. A support material 102 is applied to a substrate101 or a preceding layer. The support material 102 can be appliedaccording to the contour of the desired part 108 in a defined way or ina flat form with subsequent production of the recesses 103 needed. Therecess 103 may be larger than the contour of the desired part 108 if afinishing operation for the layer on the construction material 107 is tobe carried out. In a further step, the recess 103 is filled with aconstruction material 107. To this end a supply container 105, whichcontains the construction material 104, is guided in the direction ofarrow 106 over the recess 103 existing in the support material 102. In afurther step, the construction material 107 is molten in itself andoptionally molten (connected by melt metallurgy) with the layerpositioned thereunder with a laser 109, which moves e.g. in thedirection of arrow 110. In case an allowance was provided on part 108,said allowance can now be removed. In a further step, the whole surface111 of the layer is leveled to obtain a defined layer height. The stepsare now repeated so often that the desired part 108 is finished.Subsequently, the support material 102 is removed to expose part 108.

In a further preferred embodiment, the production of a part 200 with arecess shall be described. In this description, the production of sharpedges or small radii shall particularly be discussed. Reference is heremade to FIGS. 6 to 18. A support material 202 is applied in oneoperation to the whole surface on a substrate 201 or a preceding layer.In a further step, a recess 203 is produced in the layer just applied.In specific portions, said recess 203 has the contour of the desiredpart 200. In other portions, the final contour of the part 200 is notproduced immediately, as is e.g. the case in a known method, but alarger recess is produced so that the part 200 has an allowance atspecific places. Said larger recess 203 is needed when the radius of themachining tool is larger than the accepted radius on the later part 200or when a sharp edge is needed. In a further step, the recess 203 isfilled with a construction material 204. In a further step, theallowance on the construction material 204 is removed, and the wholesurface of the layer is leveled to obtain a defined layer height. In themachining of the contour both a part of the construction material 203and a part of the support material 202 are removed. This removal createsa new recess 205 in the layer. In a further step, support material 206is applied again. During this application two layers 206 are produced atthe same time because the layer 206 regards the filling of the recesses205 (defects in the preceding layer) and the portion positionedthereabove. The steps are now repeated so often that the desired part200 is finished. The block obtained in this way is then separated fromthe construction platform. Subsequently, the support material 202, 206is removed to expose the part 200.

In a further preferred embodiment, the production of a part 300 with arecess is described. Reference is here made to FIGS. 19 to 31. A supportmaterial 302 is applied in one operation to the whole surface on asubstrate 301 or a preceding layer. In a further step, a recess 303 isformed in the layer just applied. Said recess 303 is larger than thecontour of the desired part 300. Said larger recess 303 includes anallowance for finishing or smoothing the contour. The size of theallowance can be chosen freely or also in dependence, for instance, onthe machining or the type of application, the accuracies needed, or thegeometry. In a further step, the recess 303 is filled with aconstruction material 304. In a further step, the allowance on theconstruction material 304 is removed unless needed for a laterprocessing, and the whole surface of the layer is leveled to obtain adefined layer height. When the contour is being processed, both a partof the construction material 304 and a part of the support material 302are removed. This removal creates a new recess 305 in the layer. In afurther step, support material 306 is applied again. During applicationtwo layers 306 are produced at the same time because the layer 306regards the filling of the recesses 305 (defects of the preceding layer)and the area positioned thereabove. The steps are now repeated so oftenthat the desired part 300 is finished. The block obtained in this way isthen removed from the construction platform. Subsequently, the supportmaterial 302, 306 is removed to expose the part 300.

All of the measures and features of the invention contained in thedescription and the claims are essential features.

1. A method for producing a part, comprising the following steps: a)applying a first layer consisting of a support material; to aconstruction platform in a flat form or according to a contour of thepart; b) introducing at least one recess into said support material,wherein said recess introduced into said support material is larger atleast in portions than the contour of the desired part and thussurrounds said part with an allowance; c) filling said recess with aconstruction material; d) machining the part to form the desired contourand to remove said allowance such that both a part of said constructionmaterial and a part of said support material are removed and at leastone new recess is thus created; e) applying a further layer of supportmaterial, said further layer filling both said new recess and a furtherlayer positioned thereabove; f) repeating steps b) through e) untilcompletion of said part; and g) removing said support material.
 2. Themethod according to claim 1, wherein said construction platform isproduced as follows: a) applying a first layer of support material tothe whole required surface of a substrate; b) following thesolidification of said first layer, leveling said layer and applying afurther layer of support material, and c) repeating steps a) and b)until said construction platform has reached an adequate height toremove said part from said construction platform at a later time.
 3. Themethod according to claim 1, wherein prior to the application of a newlayer the surface of the layer positioned thereunder is leveled.
 4. Themethod according to claim 1, wherein the surface of said constructionmaterial and/or support material is activated prior to the applicationof the next layer or next material.
 5. The method according to claim 1,wherein for the production of undercuts in said support material,vertical walls are first produced at places of the undercuts.
 6. Themethod according to claim 1, wherein each of the newly applied layers initself and with the layer positioned thereunder is molten by supplyingenergy.
 7. The method according to claim 1, wherein when two or moredifferent construction materials are used, a separate recess is producedfor each construction material.
 8. The method according to claim 1,wherein the construction material applied in excess in removed on saidconstruction material.
 9. The method according to claim 1, wherein aplurality of parts are produced side by side on a construction platform.10. A device for producing a part comprising: a material applyingsection configured and arranged to selectively apply a layer of supportmaterial to a construction platform in a flat form or according to acontour of said part; and a material removing section configured andarranged to form at least one recess in said part itself or in saidsupport material that is larger than at least a portion of the contourof said part and configured to form an allowance surrounding said part,said material applying section configured and arranged to fill saidrecess with construction material, said material removing sectionconfigured and arranged to machine said part to form the desired contourand to remove said allowance by removing a part of said constructionmaterial and a part of said support material to form at least one newrecess, and said material applying section configured and arranged toapply a further layer of support material for filling both said newrecess and another layer positioned thereabove.
 11. The device accordingto claim 10, wherein said material removing section includes at leastone machining tool for said construction material and/or supportmaterial.
 12. The device according to claim 10, further comprisingsensors for automatic process monitoring.
 13. The device according toclaim 10, wherein said material removing section includes a CNC millingmachine.
 14. The device according to claim 10, wherein said materialremoving section is located within an encapsulated milling machine. 15.The device according to claim 14, wherein said material applying sectionincludes a supply means, which is arranged outside the encapsulatedmilling machine.
 16. The device according to claim 10, wherein saidmaterial removing section includes a laser device.